Single-tract Percutaneous Nephrolithotomy Research Articles

Clinical Utility of S.T.O.N.E, Guy's Scoring System, and Renal Stone Complexity Scoring in Predicting Outcome of Single-Tract Percutaneous Nephrolithotomy.

Several imaging-basedscores have been developed to predict postoperative stone-free state (SFS) and complications. This study aimed to assess the accuracyof the S.T.O.N.E., Guy Scoring System (GSS), and Seoul National University Renal Stone Complexity (S-ReSCS) scores inpredicting theoutcomes of single-tract percutaneous nephrolithotomy (ST-PCNL). This scoring system holds paramount importance for low-incomeand low-middle-income countries (LMICs), as it is inexpensive and cost-effective for the healthcare system. This retrospective study was carried out with 147 participants. Based on the preoperative computerized tomographic (CT) scan, each patient's S.T.O.N.E. score, GSS, and S-ReSCS were recorded. The modified Clavien grading system was used to document intra- and postoperative complications. The mean age of the sample population was 45 years. SFS was achieved in 110 (74.8%) patients. The number of calyces involved (p = 0.008), S.T.O.N.E. scoring (p = 0.001), GSS (p = 0.008), and S-ReSCS (0.001) correlated well with the SFS. Forty-nine (33.33%) patients developed complications. The most common complications fell within Clavien grade II. No statistical significance was noted between the S.T.O.N.E. score, GSS, and S-ReSCS with the modified Clavien grading system. The S.T.O.N.E. scoring, GSS, and S-ReSCS have a high predictive value for achieving SFS in ST-PCNL. In addition, findings from LMICs are comparable with those from the rest of the world.

Efficacy of Seoul National University Renal Stone Complexity Score for Predicting Stone Free Rate after Percutaneous Nephrolithotomy

Aim: To determine the frequency of stone clearance following single tract percutaneous nephrolithotomy and evaluate the reliability of the renal stone. Study Design: Descriptive study Place and duration of study: Department of Urology, SIUT, Karachi from 1st January 2020 to 31st October 2021. Methodology: One hundred and forty four patients were enrolled. Patients were classified into three groups, low, medium and high score group based on Seoul Renal Stone Complexity Scoring System. To determine the SFR, all patients were followed with ultrasound and X-ray KUB for 30th day after the surgery. Results: The patients' mean age was 34.51±12.57 years. The mean SReSC score was 4.00±1.96. There were 106(73.61%) males and 38(26.39%) patients were females. SReSC score was low in 71 patients (49.31%), medium in 45 patients (31.25%), and high in 28 patients (19.44%). 114(79.17%) patients were found to be stone-free. The SFR was greater among patients with a low S-ReSC score 98.6%. Conclusion: The S-ReCSC scoring system is valuable in predicting of the post PCNL stone free rate. Keywords: Seoul National University Renal Stone Complexity Score, Stone free rate, Percutaneous Nephrolithotomy.

The impact of Hounsfield unit-related variables on percutaneous nephrolithotomy outcomes

We aimed to identify the association between Hounsfield Unit(HU)-related variables and percutaneous nephrolithotomy (PCNL) outcomes. We enrolled patients with single renal stones (1–3 cm) who underwent single-tract PCNL between January 2014 and October 2019. Demographics and stone characteristics were retrospectively reviewed. Preoperative computerized tomography (CT) and follow-up CT within at least 3 months after PCNL were included in this analysis. Stone-free status was defined as residual stone measuring ≤ 2 mm within 3 months postoperatively. HU and cross-sectional area (CSA) were measured using the free-draw technique. We analyzed HU-related variables using logistic regression model for outcomes. Altogether, 188 out of 683 patients met the inclusion criteria. The stone-free rate (SFR) was 79.2%. There were no significant differences in age, sex, BMI, ASA class, laterality, pre-op shockwave lithotripsy, stone size, stone burden, skin-to-stone distance, and HU between the stone-free and remnant groups. CSA and HU/CSA in the stone-free and remnant groups were 94.5 ± 46.1 and 128.3 ± 98.5 (p = 0.043) and 10.1 ± 5.6 and 7.3 ± 3.4 (p = 0.001), respectively. Multivariate logistic regression analysis revealed that pelvis, ureteropelvic junction stones, and HU/CSA were independent predictors of SFR. HU did not affect PCNL outcomes. We believe that HU/CSA could be used for determining stone treatment plans and predicting outcomes.

One-Stage Flexible Ureteroscopy during Single-Tract Percutaneous Nephrolithotomy in the Treatment of Parallel Calyceal Stones

Introduction: The aim of this study was to compare the clinical safety and efficiency between one-stage flexible ureteroscopy (FURS) during single-tract percutaneous nephrolithotomy (PCNL) and multi-tract PCNL in the treatment of parallel calyceal stones. Methods: One hundred and twenty-five patients who had calyceal stones parallel to puncture channel from March 2017 to January 2021 were enrolled and assigned into two groups. Seventy cases received the treatment of FURS combined with single-tract PCNL under the oblique supine position (the Combined group), and 55 cases had multi-tract PCNL procedure under the prone position (the Multi-tract group). Demographic characteristics, clinical information, and surgical outcomes were analyzed. Results: Demographic variables and stone characteristics did not show statistical difference between the two groups. Compared with the Multi-tract group, there were longer operation time (p = 0.021), shorter postoperative hospitalization days (p = 0.003), smaller postoperative hemoglobin drop (p = 0.002), less incidence of moderate and severe postoperative pain (p = 0.001), and postoperative perirenal hematoma (p = 0.012) in the Combined group. No significant difference was found in the stone-free rate (SFR) and postoperative fever between the two groups (p = 0.880 and p = 0.324). More patients needed postoperative intervening embolization in the Multi-tract group (p = 0.048). Discussion/Conclusions: For most patients with parallel calyceal stones, one-stage FURS combined with single-tract PCNL procedure was a safer procedure for the reduction of complications and could achieve a comparative SFR compared to the multi-tract PCNL.

Comparison of multi-tract PCNL and single-tract ECIRS in semisupine-lithotomy position for staghorn renal calculi

Objective: To compare the outcomes of multi-tract percutaneous nephrolithotomy (PCNL) and simultaneous combined single-tract percutaneous nephrolithotomy and flexible ureteroscopic lithotripsy (ECIRS) as treatment for staghorn stones. Methods: The clinical data of patients with staghorn stones who were treated with multi-tract PCNL or single-tract ECIRS in Sun Yat-sen Memorial Hospital of Sun Yat-sen University from January 2015 to December 2019 were retrospectively analyzed. Two group of patients were placed in semisupine-lithotomy position (Galdakao-modified supine Valdivia position). We punctured into the renal calyces guided by ultrasonography. A F6 double J stent and a nephrostomy tube were routinely inserted in both groups. Kidney-ureter-bladder radiography (KUB) or computed tomography (CT) were done within 24 hours and 1 month after procedure to determine stone free rate (SFR). Stone free was defined as no residual stones or residual stones of <4 mm in diameter. The SFR, operating time, intraoperative and postoperative complications, and hospitalization time of the two groups were compared and analyzed. Results: A total of 135 patients were included in the study, 70 patients were female, 65 patients were male. The average age were 50.8 years. A total of 74 patients were managed by multi-tract PCNL, while 61 patients were treated by single-tract ECIRS. The mean stone diameter was (58.5±11.4) mm in the PCNL group and (57.7±11.6) mm in the ECIRS group (P=0.658). Neither the 24-hour SFR (81.1% vs 80.3%) nor one-month SFR (91.9% vs 90.2%) after procedure was significantly different between the groups (both P>0.05). The operating time was significantly longer in PCNL group compared with ECIRS group [130(100,171) vs 105(90,135) min, P=0.015]. The rate of Clavien-Dindo grade 2 or higher were significantly higher in the PCNL group than the ECIRS group (18.92% vs 1.64%, P<0.01). The PCNL group required longer hospitalization time than the ECIRS group [8 (7, 9) vs 6 (5, 8) d, P<0.01]. Conclusions: Both multi-tract PCNL and single-tract ECIRS treating staghorn stones in semisupine-lithotomy position are safe and effective. The two procedures have comparable SFR. However, the ECIRS group has lower rates of postoperative complications, shorter operating time and hospitalization time.

Single- versus Multiple-Tract Percutaneous Nephrolithotomy in the Surgical Management of Staghorn Stones or Complex Caliceal Calculi: A Systematic Review and Meta-analysis.

Objective To assess current evidence on the effectiveness and safety of single- versus multiple-tract percutaneous nephrolithotomy in the surgical management of complex caliceal calculi or staghorn stones through a comprehensive literature review. Methods A comprehensive literature review of articles investigating the clinical efficacy and safety of single- versus multiple-tract percutaneous nephrolithotomy was performed. Relevant literature was obtained by systematically searching PubMed, EMBASE, and the Cochrane Library through May 2020. We followed the search strategy based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. The primary outcomes, including the stone-free rate (SFR), and secondary outcomes (peri- and postoperative complications and operative data) were evaluated using RevMan 5.3 statistical software. Results Ten studies involving 1844 patients with complex caliceal calculi or staghorn stones met the inclusion criteria. Single-tract percutaneous nephrolithotomy (STPCNL) had noninferior clinical efficacy with respect to the immediate SFR (odds ratio (OR) = 0.80, 95% confidence interval (CI) (0.46 to 1.38), p = 0.42) and 3-month SFR (OR = 1.22, 95% CI (0.38 to 3.92), p = 0.74) compared with multiple-tract percutaneous nephrolithotomy (MTPCNL). In addition, pooled analyses showed that STPCNL resulted in significantly lower hemoglobin decreases (MD = −0.46, 95% CI (-0.68 to -0.25), p < 0.0001), fewer blood transfusions (OR = 0.48, 95% CI (0.34 to 0.67), p < 0.0001), and fewer pulmonary complications (OR = 0.28, 95% CI (0.09 to 0.83), p = 0.02) than MTPCNL. However, the overall evidence was insufficient to suggest a statistically significant difference for other adverse events. Conclusion This meta-analysis indicated that STPCNL is an effective method for treating complex caliceal calculi or staghorn stones. Compared with MTPCNL, STPCNL not only yields similarly high SFRs but also is associated with many advantages, less blood loss, fewer blood transfusions, and fewer pulmonary complications without an increase in other complications. However, the findings of this study should be further confirmed by well-designed prospective randomized controlled trials (RCTs) with a larger patient series.

The Correlation Between STONE Nephrolithometry Score and Hemoglobin Drop in Patients Undergoing Percutaneous Nephrolithotomy.

ObjectiveIn this study, we aimed to determine the correlation between the STONE score [(S)ize of the stone, (T)opography or location, degree of (O)bstruction of the urinary system, (N)umber of stones, and (E)valuation of Hounsfield units] and postoperative hemoglobin drop in patients undergoing percutaneous nephrolithotomy (PCNL).MethodsThis was a prospective observational study and all adult patients aged 18-65 years undergoing unilateral, single-tract PCNL using 26 Ch. Amplatz sheath for renal calculi were included. The five variables of the STONE nephrolithometry score were calculated prior to the procedure. The stone-free rates were assessed on imaging at four weeks and complications were graded using the modified Clavien system.ResultsOf the 142 patients included, 75% were below 55 years of age. More than half of our patients were diabetic with more than 60% having a body mass index (BMI) above 25 kg/m2. The mean STONE score was 7 with 33% having a high (>9) STONE score. The mean hemoglobin drop was 1.15 +0.92 g/dL with eight patients (5.63%) requiring transfusion and one (0.7%) requiring angioembolization; one patient required readmission for observation. Complete STONE clearance was achieved with PCNL alone in 78.2% of the patients. There was a significant correlation of hemoglobin drop with the STONE score, stone size, and preoperative creatinine clearance. Patients with a hemoglobin drop of >1 g/dL had a higher STONE score and mean stone size. The overall complication rate was significantly higher (10.5%) in patients with a hemoglobin drop of >1 g/dL as compared to those with a hemoglobin drop of <1 g/dL (2.8%).ConclusionStone complexity as measured by the STONE score correlates with post-PCNL hemoglobin drop, stone clearance, and complication rates. The STONE score may be used for preoperative counseling and to evaluate the potential need for transfusion.

Is multiple tract percutaneous nephrolithotomy a safe approach for staghorn calculi?

To explore the safety of multiple tract percutaneous nephrolithotomy (PNL) in terms of complication and draw a nomogram to predict the possibility of significant renal function decline (SRFD). Patients with complex renal calculi appropriate for PNL at our institution between August 2016 and February 2018 were included in the study. The outcome of single and multiple tract PNL was analyzed retrospectively. A nomogram was created to predict the probability of SRFD. 793 (88.4%) patients were treated with single tract PNL (Group 1) and 104 patients (11.6%) treated with multiple tract PNL (Group 2). Group 2 had a significantly greater hemoglobin reduction (16.0 ± 12.5 vs. 11.4 ± 11.8g/L, p < 0.001), higher rate of postoperative fever (19.2% vs. 11.9%, p = 0.034) and longer duration of the operation (110.6 ± 39.6 vs. 97.8 ± 34.5min, p < 0.001). A nomogram for predicting the probability of SRFD was constructed based on identified risk factors: patients' age, positive urine culture (UC +), hemoglobin reduction and embolization. The area of receiver operating characteristic (ROC) curve was 70%. Bootstrapping technique utilized to make the calibration plot showed a high reliability of the nomogram. Multiple tract PNL had a higher risk of hemoglobin reduction and postoperative fever than single tract PNL. Multiple tracts had no effect on SRFD, but old age, UC + , hemoglobin reduction and embolization were risk factors for SRFD. A nomogram with the aim of predicting the probability of SRFD based on these parameters demonstrated good uniformity in internal validation.

Treatment for residual stones using flexible ureteroscopy and holmium laser lithotripsy after the management of complex calculi with single-tract percutaneous nephrolithotomy.

This study validated the effectiveness and safety of the treatment for residual stones using flexible ureteroscopy (fURS) and holmium laser (0.6-1.2J, 20-30Hz) lithotripsy via a fiber with a 200-μm core diameter and 0.22 numerical aperture (NA) after the management of complex calculi with single-tract percutaneous nephrolithotomy (PCNL). Between January 2014 and June 2016, 27 consecutive patients with complex calculi underwent fURS and holmium laser lithotripsy after a planned single-tract PCNL. Among the 27 patients with complex calculi, 9 had full staghorn calculi, 7 had partial staghorn calculi, and 11 had multiple calculi. After the first single-tract PCNL session, the mean stone size and mean stone surface area were 18.0 ± 10.7mm and 181.9 ± 172.2mm2, respectively. Treatment for residual stones with fURS and holmium laser lithotripsy was successfully completed and was performed without intraoperative complications. The mean operative time of the fURS procedure was 69.1 ± 23.6min, and the mean hospital stay was 5.3 ± 2.4days. The mean decrease in the hemoglobin level was 7.3 ± 6.5g/l. After the fURS procedure, the overall stone-free rate was 88.9%. The overall postoperative complication rate was 14.8% (Clavien grade I 11.1%; Clavien grade II 3.7%). The current approach tested here combines the advantages of both PCNL and fURS and effectively manages complex calculi with a high stone-free rate (SFR) (88.9%). This approach also reduced the number of treatment sessions, the number of percutaneous access tracts, and the blood loss and potential morbidity associated with multiple tracts.

Prospective evaluation of outcome of percutaneous nephrolithotomy using the ‘STONE’ nephrolithometry score: A single-centre experience

ObjectiveTo assess the prediction of stone clearance and complications of percutaneous nephrolithotomy (PCNL) using the ‘STONE’ nephrolithometry score, assessing stone size, tract length (skin-to-stone distance), degree of obstruction, number of calyces involved and stone essence (density). Patients and methodsThis was a prospective study of patients undergoing single-tract PCNL while prone, conducted at a university hospital. All patients had non-contrast-enhanced computed tomography within 3weeks of the procedure. Only patients with a unilateral procedure and radio-opaque stones were included. The five variables of the STONE nephrolithometry score were calculated before the procedure. The stone-free rates were assessed with a plain abdominal film at 4weeks and complications were graded using the modified Clavien system. ResultsIn all, 107 patients were included in the final analysis. Overall, 80% of patients were rendered stone-free. Among the individual variables, a larger stone (P=0.002) and the involvement of multiple calyces (P=0.04) were associated with residual stones, while tract length (skin-to-stone distance), stone density and presence of hydronephrosis were not. Patients who were rendered stone-free had a statistically significant lower overall STONE score than those with residual stones, at 7.24 vs. 8.14 (P=0.02). The score also correlated with operative duration, which was significantly longer with a higher STONE score (P=0.03). The complication rate was 18% and most complications were Clavien grade 2, with bleeding requiring a blood transfusion (11 patients) being the commonest. There were no deaths within 30days of surgery, but there was no correlation between the STONE score and complications. ConclusionThe STONE nephrolithometry score is a simple and easy to apply system for predicting complexity in stone clearance with PCNL.

Which is the preferred modality of renal access for a trainee urologist: ultrasonography or fluoroscopy? Results of a prospective randomized trial.

In percutaneous nephrolithotomy (PCNL), placement of the access tract into the kidney is an important aspect of the procedure and is responsible for the steep learning curve associated with the operation. The aim of the current prospective randomized trial was to assess the duration of radiation exposure along with the safety and efficacy of PCNL done by a trainee, utilizing either ultrasonography (US) or fluoroscopic guidance to obtain access. Sixty-four patients with ≤3 cm renal calculi undergoing single-tract PCNL by trainee urologists (experience of <25 PCNL's) were randomized into US- and fluoroscopic-guided access groups (32 in each). In Group 1 (US guided), puncture was done using a 3.5/5 MHz US probe with a puncture attachment, whereas the triangulation technique with biplanar C-arm fluoroscopy was utilized in group 2 (fluoroscopic guided). Patient demographics, stone parameters, intraoperative characteristics, fluoroscopy durations, and postoperative outcomes were analyzed. Both groups were comparable as far as patient and stone characteristics were concerned. The fluoroscopy exposure during the puncture phase (T2) and overall (T) was significantly lower in the US group at 9.0±20.8 vs 43.8±34.8, (p<0.0001) and 204.3±84 vs 239.9±77.5, (p=0.04). Six patients in group1 required fluoroscopic adjustment (p=0.03). All other intra- and postoperative parameters were similar in both the groups. Both ultrasound and fluoroscopic guidance for renal access are equally safe and feasible in the hands of a trainee urologist. Total fluoroscopy duration and exposure time during puncture were both significantly less in the ultrasound group. Expertise in fluoroscopic-guided access is essential for a novice to effectively achieve access in all possible situations.

Clinical application of S.T.O.N.E.nephrolithometry for preoperative evaluation of percutaneous nephrolithotomy

Objective To explore the feasibility and practicality of S.T.O.N.E.nephrolithometry during percutaneous nephrolithotomy (PCNL).Methods Clinical data of 72 patients who underwent PCNL between October 2012 and May 2013 were analyzed retrospectively.Two surgeons evaluated the scores of S.T.O.N.E.nephrolithometry for patients.The scores were analyzed by Stata 12.0 via kappa test.The difference in the number of tract was measured by Stata 12.0 via One-way ANOVA.The relationship between S.T.O.N.E.scores and stone-free rate was valuated by logistic analysis.Results Of 72 cases subject to PCNL,64 cases were operated via single tract PCNL,and 8 cases via two tracts PCNL.The stone size was (613.99 ±566.05) mm2.There were 31 cases of left stone (43.06％),and 41 cases of right stone (56.94％).The time for tract access was (19.0 ± 25.1) min.Stone extraction time was (33.2 ±45.5) min.The incidence of complications was 6.9％.Average hospital stay was 13 days (5-56 days).The value of S.T.O.N.E.Nephrolithometry for different variances via kappa test was 0.64-0.83 between two doctors with the difference being significant (P ＜ 0.05).The case number in groups of low,middle,and high scores was 39,21,and 12 respectively.There was significant difference in number of tract among three groups (P ＜ 0.05).The time of access tract showed no significant difference among three groups (P ＞ 0.05).Meanwhile,the relationship between S.T.O.N.E.scores and stone-free rate was significant (r =0.83,P ＜ 0.01).Conclusion S.T.O.N.E.Nephrolithometry was objectively used to evaluate the difficulty for PCNL,and the difficulty for PCNL was quantified via S.T.O.N.E.Nephrolithometry. Key words: Renal stone ratings; Percutaneous nephrolithotomy; Renal stone

External Validation and Evaluation of Reliability and Validity of the S-ReSC Scoring System to Predict Stone-Free Status after Percutaneous Nephrolithotomy

ObjectivesThe Seoul National University Renal Stone Complexity (S-ReSC) scoring system was developed to predict the stone-free rate (SFR) after single-tract percutaneous nephrolithotomy (PCNL). This study is an external validation of this scoring system.Materials and methodsA retrospective review included 327 patients who underwent PCNL at 2 tertiary referral centers. The S-ReSC score was assigned from 1 to 9 based on the number of sites involved. The stone free status was defined as either complete clearance or clinically insignificant residual fragments <4 mm in size at 1 month follow-up imaging. Inter-observer and test-retest reliabilities were evaluated. The statistical performance of the prediction model was assessed by its predictive accuracy, predictive probability, and clinical usefulness.ResultsThe overall SFR was 65.4%. SFRs were 83.9%, 47.6%, and 21.4% in low (1–2), intermediate (3–4), and high (5–9) score groups, respectively, with significant differences (P<0.001). Inter-observer and test-retest reliabilities revealed almost perfect agreements. External validation of the S-ReSC scoring system revealed an AUC of 0.731 (95% CI 0.675–0.788). The AUC of 3-titered S-ReSC score groups was 0.691 (95% CI, 0.629–0.753). The calibration plot showed that the predicted probability of SFR had a concordance comparable to that of the observed frequency. The Hosmer–Lemeshow goodness-of-fit statistic revealed an adequate performance of the predictive model (P = 0.10). Inter-observer and test-retest reliability showed a good level of agreement.ConclusionsThe S-ReSC scoring system is useful in predicting the post-PCNL SFR and in describing the complexity of renal stones.

Combination of debulking single-tract percutaneous nephrolithotomy followed by retrograde intrarenal surgery for staghorn stones in solitary kidneys

Objective. The aim of this study was to report a therapeutic approach comprising a combination of debulking single-tract percutaneous nephrolithotomy (PCNL) and subsequent retrograde intrarenal surgery (RIRS) for treatment of staghorn stones in patients with solitary kidney. Materials and methods. A retrospective review was undertaken of 56 patients with staghorn stones in a solitary kidney who underwent the above-mentioned combination therapy. PCNL was first performed for stone debulking and RIRS was then used to remove residual stones after an interval of 2–4 days. Data were collected on operative parameters, stone-free rate (SFR), complications and renal functions. Results. The staghorn stones had a mean stone burden of 2548 ± 1028 mm2 (range 1438–3956 mm2). The SFR after 3 months was 89.3%. The overall blood transfusion rate was 7.1%. Complications were observed in nine patients (16.1%), including selective renal artery embolization, fever, gross haematuria and steinstrasse in one, two, three and three cases, respectively. At a mean follow-up of 31 months, available in 38 patients, kidney function was stable in 71%, improved in 26.3% and worsened in 2.7%, according to serum creatinine levels that remained within ±20%, or that increased or decreased outside this range. No patient required haemodialysis. Conclusions. Combining single-tract PCNL with subsequent RIRS was an effective strategic option for treating staghorn stones in solitary kidneys. The method gave an excellent SFR, satisfactory preservation of renal function, reduced bleeding risk and potentially less morbidity than that associated with multiple-tract PCNL.

Evaluation of a Novel Fascial Dilator Modified with Scale Marker in Percutaneous Nephrolithotomy for Reducing the X-Ray Exposure: A Randomized Clinical Study

To evaluate the role of the fascial dilators modified with a scale marker in reducing fluoroscopy time during percutaneous nephrolithotomy (PCNL). In a randomized clinical trial, eligible 100 consecutive patients anticipated to undergo single-tract PCNL were randomly assigned into two groups by the closed envelope method, to compare the efficacy and safety of the modified scale fascial dilator (group 1, n=50) and traditional nonscale fascial dilator (group 2, n=50) with respect to the X-ray exposure duration as well as the outcome of PCNL. There was no significant difference between group 1 and group 2 regarding to the initial successful access rate (100% v 96%), operative time (79.4 v 83.7 minutes), the initial stone-free rate (82% v 81.3%), complications (24% v 20%), and bleeding required blood transfusion (4% v 6%) (all p>0.05). The mean operative duration and fluoroscopic time for tract dilation in group 1 and group 2 were 164.4 ± 19 seconds v 168.3 ± 14 seconds, and 3.2 ± 0.9 seconds v 22.2 ± 4.6 seconds, (p=0.250 and p<0.001), respectively. Compared to the use of nonscaled dilators, using the scaled fascial dilators for a percutaneous access in PCNL was found to be associated with less radiation hazards along with similar stone-free rate and complications.

Seoul National University Renal Stone Complexity Score for Predicting Stone-Free Rate after Percutaneous Nephrolithotomy

ObjectivesCurrently, no standardized method is available to predict success rate after percutaneous nephrolithotomy. We devised and validated the Seoul National University Renal Stone Complexity (S-ReSC) scoring system for predicting the stone-free rate after single-tract percutaneous nephrolithotomy (sPCNL).Patients and MethodsThe data of 155 consecutive patients who underwent sPCNL were retrospectively analyzed. Preoperative computed tomography images were reviewed. The S-ReSC score was assigned from 1 to 9 based on the number of sites involved in the renal pelvis (#1), superior and inferior major calyceal groups (#2–3), and anterior and posterior minor calyceal groups of the superior (#4–5), middle (#6–7), and inferior calyx (#8–9). The inter- and intra-observer agreements were accessed using the weighted kappa (κ). The stone-free rate and complication rate were evaluated according to the S-ReSC score. The predictive accuracy of the S-ReSC score was assessed using the area under the receiver operating characteristic curve (AUC).ResultsThe overall SFR was 72.3%. The mean S-ReSC score was 3.15±2.1. The weighted kappas for the inter- and intra-observer agreements were 0.832 and 0.982, respectively. The SFRs in low (1 and 2), medium (3 and 4), and high (5 or higher) S-ReSC scores were 96.0%, 69.0%, and 28.9%, respectively (p<0.001). The predictive accuracy was very high (AUC 0.860). After adjusting for other variables, the S-ReSC score was still a significant predictor of the SFR by multiple logistic regression. The complication rates were increased to low (18.7%), medium (28.6%), and high (34.2%) (p = 0.166).ConclusionsThe S-ReSC scoring system is easy to use and reproducible. This score accurately predicts the stone-free rate after sPCNL. Furthermore, this score represents the complexity of surgery.

A Nephrolithometric Nomogram to Predict Treatment Success of Percutaneous Nephrolithotomy

Imaging is routinely done preoperatively and postoperatively to assess patients treated with percutaneous nephrolithotomy. We developed a nomogram for percutaneous nephrolithotomy success. From November 2007 to December 2009 the CROES (Clinical Research Office of the Endourological Society) collected data on consecutive patients at 96 centers globally. Patients were evaluated for stone-free status using plain x-ray of the kidneys, ureters and bladder. Treatment success was defined as no visible stones or residual fragments less than 4 mm. Multivariate regression was used to model the relationship between preoperative descriptors and the stone-free rate. Variables included case load, prior treatment, body mass index, staghorn stones, renal anomalies, and stone burden, location and count. Bootstrapping techniques were used to validate the model. Adjusted chi-square statistic values were used to rank the prognostic value of variables. A nomogram was developed using significant predictors from the model. We assessed the predictive accuracy of the nomogram using the ROC curve AUC. The nomogram was calibrated. Stone burden was the best predictor of the stone-free rate (chi-square = 30.27, p <0.001). Other factors associated with the stone-free rate were case volume (chi-square = 35.75, p <0.001), prior stone treatment (chi-square = 14.55, p <0.012), staghorn stone (adjusted chi-square = 4.73, p <0.029), stone location (chi-square = 14.74, p <0.001) and stone count (chi-square = 4.78, p <0.004). A nephrolithometric nomogram was developed with predictive accuracy (AUC 0.76). The percutaneous nephrolithotomy stone-free rate can be predicted using preclinical data and radiological information. We present a nephrolithometric nomogram for percutaneous nephrolithotomy.

Time-dependent oxidative stress effects of percutaneous nephrolithotomy

Aim of this study was to investigate the effects of operation time of percutaneous nephrolithotomy (PCNL) on renal function and hemodynamic response. Thirty-four patients (14 male, 20 female) with normal renal function who underwent unilateral single-tract PCNL between December 2010 and June 2011 were included in the study. The age, sex, stone size, grade of hydronephrosis, operative time, access pole, shock number of lithotripter, complications, stone-free rate, and hemodynamic parameters during operation were recorded. Total blood count and oxidative stress parameters such as paraoxonase1 (PON1), total antioxidant status (TAS), total oxidant status (TOS), and malonyldialdehyde (MDA) levels were examined before the operation as baseline levels and then at 30, 60, 90, and 120min during the operation. The mean age of the patients was 31.4±18.8 (9-66years)years. Mean stone size was 35.5±15.6mm. Mean serum BUN and creatinine did not change postoperatively (p>0.05), whereas mean WBC and 24-h urine cortisol were positively and hematocrite were negatively changed significantly (p<0.05). Oxidative stress parameters such as PON1 and TAS showed statistically significant decreases, while TOS and MDA showed statistically significant increases with increased operation time, especially after 1h (p<0.005). A bivariate correlation test showed correlation between oxidative stress parameters and operation time (p=0.002), but no correlation was found between oxidative stress parameters and other parameters (p>0.05). Oxidative stress and response to it increased with increasing operative time during a PCNL procedure, especially after 1h. Further studies with a larger and longer series should be performed to clarify this issue further.

Predictors of Immediate Postoperative Outcome of Single-tract Percutaneous Nephrolithotomy

To evaluate the efficacy of single tract percutaneous nephrolithotomy (sPCNL) and investigate the preoperative predictive factors associated with stone clearance after sPCNL. A retrospective review of 351 cases of sPCNL performed at a single institution by 1 of 2 endourologists between January 2000 and March 2010 was performed. The primary outcome evaluated was stone-free rate (SFR) as assessed immediately after either an initial procedure or a second-look nephroscopy performed on postoperative day 2. Preoperative patient and stone factors, including age, sex, body mass index (BMI), preoperative hematocrit and creatinine, previous surgeries, comorbidities, renal anomalies, stone size, shape, location, and history of any previous treatment to the active stone burden were included in the univariate analysis. Significant or clinically relevant factors on univariate analysis were included in a logistic regression the multivariate analysis. SFR after either an initial procedure or a second-look nephroscopy was 76%. On univariate analysis, rising preoperative creatinine, hypertension, increasing stone diameter, complete staghorn stone, presence of stones in the upper pole and absence of prior SWL were associated with lower SFR. Stone size, presence of stones in the upper pole, and prior SWL for the active burden were independent predictors of SFR on multivariate analysis. sPCNL is an efficient procedure to clear renal stones, especially when used in conjunction with routine second-look nephroscopy. Increasing stone size and upper pole stones are associated with lower rates of stone clearance, whereas SWL performed before percutaneous nephrolithotomy (PCNL) is associated with improved stone clearance. The role of SWL before PCNL warrants further prospective investigation.

Editorial Comment

The American Urological Association Guidelines recommend percutaneous nephrolithotomy (PCNL) as the standard of care for patients with staghorn or large renal stones because of the high stone-free rates (SFRs) with minimal morbidity. 1 Preminger G.M. Assimos D.G. Lingeman J.E. et al. AUA guideline on management of staghorn calculi: diagnosis and treatment recommendations. J Urol. 2005; 173: 1991-2000 Abstract Full Text Full Text PDF PubMed Scopus (725) Google Scholar Before the advent of flexible fiberoptic instruments and Holmium laser lithotripters, it was not unusual for PCNL to require multiple access tracts directly on calyces containing stones to achieve stone-free status. Some authors even suggested performing auxiliary procedures, such as shock wave lithotripsy (SWL) as combination or “sandwich” therapy with PCNL to fragment stones that could not be reached using rigid instruments. However, SFRs were lower when SWL was not followed with PCNL to remove stone fragments. With the invention of flexible nephroscopes and ureteroscopes in addition to the availability of flexible miniaturized lithotripters, such as Holmium laser using 200- or 365-μm fibers, PCNL through a single incision and a single tract (sPCNL) becomes possible for large renal stones and even staghorns. In the above manuscript, the authors present a retrospective series of 351 patients who underwent sPCNL from 2000 to 2010. 2 Shahrour K, Tmoaszewski J, Ortiz T, et al. Predictors of immediate post-operative outcome of single-tract percutaneous nephrolithotomy. Urology. 17057. Google Scholar Although this method was first proposed by Wong and Leveillee, 3 Wong C. Leveillee R.J. Single upper-pole percutaneous access for treatment of ≥ 5-cm complex branched staghorn calculi: is Shock wave lithotripsy necessary?. J Endourol. 2002; 16: 477-481 Crossref PubMed Scopus (84) Google Scholar the authors should be commended for their meticulous collection of data over the 10-year period. In addition to limiting the incision to a single site (laparo-endoscopic single site [LESS), they also used a flexible ureteroscope through a natural orifice (urethra) during second-look nephroscopy to access calyces inaccessible using a flexible nephroscope; thus combining LESS with natural orifice transurethral endoscopic surgery (NOTES). Predictors of Immediate Postoperative Outcome of Single-tract Percutaneous NephrolithotomyUrologyVol. 80Issue 1PreviewTo evaluate the efficacy of single tract percutaneous nephrolithotomy (sPCNL) and investigate the preoperative predictive factors associated with stone clearance after sPCNL. Full-Text PDF